There are some real advantages to hacking into the wee hours of the morning, this gem of a screenshot is one of the best of late.
Thing is, I'm sitting here after refactoring several hundred lines of code and fixing two typos that was causing our normalisation cubemaps to be bugged, staring at this window, and unable to understand why.
The rainbow effect is obviously from the normalisation cubemap, a data construct that maps tangent-space bumpmaps to object-space on the video card (without shaders). I just can't determine at this late hour why it's showing up instead of rendering the bumpmap as it used to.
I'm sure it'll make much more sense after 8 hours sleep. In the meantime, enjoy the screenshot, or compile PySoy from subversion and run